Weighing the keyboard

Video of 4xxYTIUY9uE

Weighing-off the keyboard standardises the resistance the pianists feels across the keyboard when he presses the keys.
This is achieved by inserting small lead weights into the side of each key: they range from a maximum of 52 grams in the bass keys to a minimum of 48 grams in treble keys.
By inserting the weights, one compensates for the weight of the hammers, which are heavier in the bass than the treble.
By using sample weights, the technician determines, key by key, the weight and the position required for each lead weight to be inserted into the side of the key.